Update typing to be compatible with 3.9

tests/rcon_server.py

@@ -6,6 +6,7 @@
 
 import asyncio
 import struct
+import typing as t
 
 from aiomcrcon.client import MessageType
 
@@ -37,7 +38,7 @@ async def read_bytes(cls, reader: asyncio.StreamReader, n: int) -> bytes:
         return out
 
     @classmethod
-    async def read_packet(cls, reader: asyncio.StreamReader) -> tuple[int, int, bytes] | None:
+    async def read_packet(cls, reader: asyncio.StreamReader) -> t.Tuple[int, int, bytes] | None:
         header_data = await cls.read_bytes(reader, cls.packet_HEADER_SIZE)
 
         if not header_data: